Parameter count, complexity. The parameter count in the gating is \(2\times (27\cdot {C}{2}) = 27\cdot C\)  and that of the fusion module is \(2\times (2\cdot 3\cdot 3) = 36\) . The total parameter overhead introduced by gsf is \(27\cdot C + 36\approx 27\cdot C\)  since \(C\gg 36\)  in practice. On the other hand, a typical C3D block such as the \(3\times 1\times 1\)  used in S3D [1]} (Fig. REF ) has a parameter count of \(C_{out}\cdot C\cdot 3\)  where \(C_{out}\ge C\) . Thus the parameter overhead introduced by GSF is far less than that of a C3D block since \(27\ll 3\cdot C_{out}\) .
